The proposed research is designed to furnish quantitative and qualitative information about the fate of inhaled coal dust from different sources when laboratory animals are exposed. Inhalation exposures are to simulate concentrations of dust found in coal mines. It is planned to assess the relative importance of dust concentration, metal content, free silica, and organic extractable on the observed differences in prevalence of CWP in Appalachian vs Utah mines. A secondary goal is to provide more scientific evidence for the hypothesized role of alveolar macrophages in pulmonary disease. It is expected that the information from animals will be extrapolated for the evaluation of hazards to man.